Recirculating air cleaner



Nov. 22, 1966 s. B. WELCH RECIRCULATING AIR CLEANER 2 Sheets-Sheet 2 Filed Nov. 14, 1963 INVENTOR STANLEY B. WELCH BY gl ff Z H l5 ATTORNEY United States Patent O 3,286,445 RECIRCULATING AIR CLEANER Stanley B. Welch, Louisville, Ky., assignor to General Electric Company, a corporation of New York Filed Nov. 14, 1963, Ser. No. 323,771 6 Claims. (Cl. 55-350) The present invention relates to a recirculating air cleaner and particularly one that is for use in the kitchen and is adapted to be mounted above the cooktop of a domestic range. It is of primary importance to be able to perform the air cleaning operation with reliability and for a long period of time so that it will be unnecessary to vent the air cleaner to the outside atmosphere, but instead the regenerated air may be returned directly to the kitchen atmosphere.

It is well recognized that from the consumers point of view it is preferable to vent a kitchen hood to the outside atmosphere, but from the manufacturers point of view it is also apparent that such a vented hood design has limited demand because it is largely marketed to house builders for new home construction. This is true because of the high cost of installing the venting system in an existing home. This is especially expensive and diicult in a two-story dwelling. Admittedly, thisnew construction market is only a small fraction of the total. number of homes existing in this country.`

Recirculating kitchen hoods have been introduced on the market heretofore, but they have not 'been universally accepted, probably because they have followed too closely the design of vented kitchen hoods except that the exhaust is dumped back into the kitchen rather than being discharged to the outside atmosphere. Part of the difficulty arises because of the inability of moving a large enough quantity of air through the device while performing a satisfactory job of cleaning the air. By this is meant that frequently the lter mediums would become loaded with soil and clog up after a short period of time, land the result would be that the use of a non-vented hood would be more objectionable than no hood at all.

The principal object of the present invention is to provide a recirculating air cleaner with a plurality of filtering mediums and a divided air exhaust means having a main exhaust port and a secondary exhaust port where the exhaust to the secondary port bypasses at least one of the filtering mediums.

A further object of the present invention is to provide a recirculating air cleaner of the class described where the secondary exhaust port is of thin elongated shape and is directed downward to form an air curtain that counteracts the tendency to form an upward air stream from the cooktop that would normally be induced by the main exhaust stream.

A further object of the present invention is to provide a recirculating air cleaner having an inclined bottom wall cooperating with an elongated front intake port having streamlining means to reduce the air pressure loss thereat as well as to separate out the large grease particles and to render this area easy to clean.

A still further object of the present invention is to provide a recirculating air cleaner of the class described with a novel air intake port design for removing most of the airborne soil before it passes into the air cleaner.

The present invention, in accordance with one form thereof, is embodied in a recirculating air cleaner that comprises a hollow housing with an air inlet port and a first filter medium interposed in the inlet port. A second filter medium is positionedv in a plenum chamber downstream of the first filter medium, while a motor-blower unit draws air from the plenum chamber and divides its exhaust into a main exhaust port as well as a secondary ICC exhaust port. A third filter medium is located within the main exhaust port. The secondary exhaust port is of thin elongated shape for discharging air in a downward direction in the manner of an air curtain so as to direct the intake air from an underlying cooktop toward the intake port.

My invention will be better understood from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.

FIGURE 1 is a top perspective view of a recirculating air cleaner embodying the present invention with parts broken away and some in cross-section to show the second plenum and a diffuser at the discharge end of the motor-blower unit, as well as a third filter medium in the main exhaust port for discharging air in an upward direction from the front portion of the top wall of the housing.

FIGURE 2 is atransverse cross-sectional elevational view taken through the motor-blower `unit on the right side along line 2-2 of FIGURE l.

FIGURE 3 is'an exploded view of the particulate filter medium or second filter utilized in the present invention.

Turning now to a consideration of the drawings and in particular to FIGURE 1 there is shown a recirculating ,air cleaner 10 that comprises a hollow sheet rnetal housing 11 of -box-like shape having a front wall 12 that also Aserves as a control panel, a back wall 13, opposite side walls 14 and 15, avstepped top wall 16 (best seen in FIGURE 2) as-well as an inclined bottom wall 17 which will be better understood hereinafter. In other words, this recirculating air cleaner 10 is not a hood in the strict sense of the word as it is understood in the present state of the art. A kitchen hood is generally understood to be a concave air collector assembly minus a bottom wall, but having all other walls of a box such as front, back, sides and top. It has been discovered with repeated testing that the typical kitchen hood is of very little value in capturing or collecting air that rises from a range cooktop and particularly the front heating lunits thereof and directing the air into a suction or exhaust system of the hood. Hence, a principal distinction between this invention and the prior art is that a preferred embodiment of the present invention incorporates a box-like hollow housing having all of its walls rather than a hood design that is absent a bottom wall.

A second distinction is that an elongated air intake port 19 is located in the bottom wall 17 adjacent the front wall 12 of the hollow housing. Notice that the bottom wall 17 is inclined upwardly from back to front, and that it has been lowered as much as possible without interfering with the backsplash of the range (not shown) and tall cooking utensils such as coffee pots and kettles that would be located on the surface units. This yields maximum horizontal air velocities across the cooktop, and the inclined wall 17 serves to direct the air from the rear heating units upwardly and forwardly to the air intake port 19 at the front of the housing. This intake port 19 extends for nearly the complete Width of the housing and it has been found desirable to provide a streamlining effect by use of the lower curved lip 20 and the upper inclined wall or impact plate 21 so as to minimize the air pressure loss at the intake port. This streamlining effect gradually decreases the size or throat of the port between the curved surface 20 and the impact plate 21.

Another advantage of this streamlining effect is that air will be drawn into Ithe housing at a fairly high velocity and it must turn a rather sharp corner and reverse its direction as it enters. As a result many of the larger soil particles are thrown out of the air stream by centrifugal force and they tend to adhere to the impact plate 21. This plate 21 is in an accessible location so that it may be sponged clean without unfastening and lowering the bottom wall 17. The bottom wall 17 is formed by a pivoted cover member 23 which is vhinged at the back wall 13 along the hinge axis 24. Suitable fasteners 25 extend through the cover and are threaded into bracket means 26 at suitably spaced locations. Thus, by removing the fasteners 25, the cover 23 or bottom wall 17 may be dropped for ease in replacing filters as will be better understood hereinafter.

A first filter medium 28 is positioned adjacent the inlet port 19 as for example a grease filter formed of close mesh expanded aluminum. Such a filter is a permanent filtering means which may be removed and cleaned with soap and water in the sink for reuse. A large plenum chamber 30 comprises a major portion of the housing 10 and it is located downstream of the first filtering medium 28 and circumscribed by said filtering medium 28, the back wall 13, the bottom wall 17, side Walls 14 and 15 and a horizontal partition 31 at the top thereof. This top partition 31 can also be seen `in FIGURE 1 and its function is to separate the first plenum chamber 30 from a second overhead plenum chamber 33 which is defined by the partition 31, the back wall 13, the top Wall 16 and side walls 14 and 15. It should be understood that the partition 31 angles up at the front as at 34 to form an air exhaust port 35 that Iis located in the front portion of the top wall 16. This exhaust -port 35 is covered by an open grill work 36 as is best understood from FIG- URE 1. This grill Work has a large number of slotted openings 37 that serve to direct the exhaust air in an upward direction to parallel the front doors of wall-hung cabinets (not shown) under which this air cleaner 10 would ordinarily be mounted.

A second filter medium 39 is a particulate filter in the form of a folded sheet or bag of fine fiber fiberglass. There is a high air pressure drop across the entire fiberglass sheet so that the air pressure at any point on the surface of the filter bag is substantially equal. Looking at FIGURE 3 the filter 39 is made up of three main elements; namely, an inner frame 41 of widely spaced welded wire construction 42 formed in an elongated arch shape that is provided with a supporting base member or frame 43. A second element is the large sheet of fiberglass 44 that is adapted to drape over the inner Wire form 41 as well as to be folded around the ends thereof so as not to become separated. This does not mean that the sheet closes the two ends of the arched form, although this may be considered desirable by some in an attempt to avoid the need for a hold-down means. The fiberglass 44 is designed to be held to the inner frame 41 by a similar outer frame 46 tha-t is capable of nesting or telescoping over the first frame 41 after the sheet of fiberglass 44 has been placed over the first frame. Suitable fastening means are used to suspend the second filtering medium 39 in the first plenum chamber 30 from the support frame 43 and rela-ted bracket members.

The horizontal partition 31 is provided with a small circular opening 48 in which is mounted a motor-blower unit 49 comprising an electric motor 50, a sirocco blower wheel 51 and suitable mounting brackets 52 which are radially spaced around the motor 50 and fastened to the edge of the opening 48. The blower wheel 51 is located in the second plenum chamber 33 and it is adapted to draw air through the first two filtering mediums 28 and 39 and from the first plenum chamber 30 into the second plenum chamber 33. Looking at FIGURE 1, a curved metal band or scroll 54 is centered around the blower wheel 51 so as to confine the discharge air from the blower and cause the air to expand gradually by forming a diffuser` section 55 of diverging shape with respect to the back wall 13 of the plenum 33. Thus, the diffuser 54 is effective in converting some of the velocity pressure of the air to static pressure. Also, the side wall 14 of the plenum 33 has been modified by a curved barrier 56 which serves to redirect some of the exhaust air toward the front of the housing and especially toward the main exhaust port 35. A third fil-ter medium 58 such as a charcoal filter is interposed over the main air exhaust port and behind the grill 36 so as to remove the odors from the air before the regenerated air 1s returned to the kitchen atmosphere.

A principal feature of the present invention is a secondary air exhaust port 60 of elongated shape which is located in the bottom wall 17 of the housing to the front of the air intake port 19 as is best seen in FIGURE 2. This secondary exhaust port is of thinline shape having a spacing of about 1A that extends for nearly the complete width of the housing, and it is fed by tapered duct work 61 which communicates with the second plenum chamber 33 through the inclined partition section 34. Hence it will be understood that part of the exhaust air bypasses the third filter medium or charcoal filter 58 and Yis discharged in a downward direction through the secondary exhaust port60 so as to form an air curtain that is directed toward the front portion of the cooktop of a domestic range. This narrow slot would handle air at a rate of about l0'to 20 cubic feet per minute. The advantage of this air curtain is to counteract an upward air streamthat would normally be induced by the main exhaust stream from port 35 so that most, if not all, of the air rising from the cooktop will be directed toward the air intake port 19.

The control panel 12 at the front of the housing is shown with two individual switches 63 and 64, where one controls the operation of the motor 50 of the air handling apparatus,while the second switch controls an illumination means such as a fluorescent lamp 65 as seen in FIG- URE 2 located behind the bottom wall 17. Actually, this lamp is mounted in a lamp housing 6 that is fixed to the back side of the pivoted cover 23. A suitable elongated opening 67 is formed in the cover and is provided'with a translucent shield or crystal'68 so that the light from the fluorescent lamp will shine down onto the cooktop of the range. Moreover, the control panel 12 is shown as including four multiple pushbutton switches 69 which would be the selector switch means for the four heating elements mounted in the cooktop of an electric range.

Modifications of this invention will occur to those skilled in this art therefore it is to be understood that this invention is not limited to the particular embodiments disclosed but that it is intended to cover all modifications which are within the true spirit and scope of the invention as claimed.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A recirculating air cleaner that is adapted to be mounted above a cooktop of a domestic range comprising walls forming a hollow housing of box-like shape, a bottom wall of the housing having near the front edge thereof an elongated air intake port, a grease filter medium positioned downstream of the air intake port, a plenum chamber positioned downstream of the grease filter medium, a particulate filter medium positioned in the plenum chamber, a motor-blower unit mounted in the housing and cooperating with the plenum chamber, and a `divided air exhaust means comprising a main exhaust port in a top wall of the housing adjacent the front edge thereof and extending for nearly the complete width thereof for directing the air in an upwardly direction, a charcoal filter medium positioned in the main exhaust port, a secondary exhaust port of thin elongated shape in the bottom wall of the housing adjacent the front edge thereof, and duct work adjacent the main exhaust port fo`r drawing off some of the air to the secondary air exhaust port so as to direct air in a downwardly direction in the manner of an air curtain.

2. A recirculating air cleaner that is adapted to be mounted above a cooktop of a domestic range comprising walls forming a hollow box-like housing having bottom and top walls, opposite side walls, a back and a front wall, an elongated air intake port in the bottom wall near the front edge thereof, a grease filter medium positioned downstream of the intake port, a plenum chamber positioned downstream of the grease filter medium, a particulate filter medium in the plenum chamber, a second plenum chamber, a small -opening forming a connection between the two plenum chambers, and a motor-blower unit having means for mounting the unit in said opening, and a gradually diverging diffuser com'bined with the blower and effective in converting some of the Veloc-ity air pressure into static air pressure, and a main air exhaust port in the top wall of the housing for nearly the complete width thereof and being adjacent the front portion for discharging the air in an upwardly direction, and a charcoal filter medium interposed over the exhaust port, and a secondary exhaust port of elongated thin slot form in the bottom wall to the front of the air intake port, and duct work adjacent the main exhaust port for drawing off some of the air to the seconda-ry air exhaust port so as to discharge the air in a downwardly directed curtain.

3. A recirculating air cleaner that is adapted to be located above a cooktop of a domestic range, said air cleaner comprising walls forming a hollow housing having an air inlet port, a first filter medium interposed in the inlet port, a plenum chamber positioned downstream of the first filter medium, a second filter medium positioned in the plenum chamber, a motor-blower unit mounted in the housing for drawing air from the said plenum cha'mber, and a main air exhaust port connected with the blower, there being a third filter medium located within said main exhaust port, and a secondary exhaust port connected with the 'blower and being of thin elongated shape, and duct work adjacent the main exhaust port for drawing off some of the air to the secondary air exhaust port so as to discharge air in a downward direction toward the cooktop in the manner of an air curtain so as to direct the air beneath the housing toward the intake port.

4. A recirculating air cleaner that is adapted to be mounted above a cooktop of a domestic range, said -air cleaner comprising a hollow box-like housing having top and bottom walls, opposite side walls, and front and back walls, the bottom wall being slightly inclined upwardly from back to front, an elongated air intake port in the bottom wall near the front edge and extending for nearly the complete width thereof, the back edge of the inlet port being rounded to give a streamlining effect with an overlying impact plate, the said port also being gradually reduced in cross-sectional area from front to back thereof so as to minimize the air pressure loss in the intake port, a grease filter medium located in the intake port, a first plenum chamber downstream of the intake port, 'and a partioulate filter positioned in the plenum chamber, a second plenum chamber separated from the first chamber by a partition, a small opening formed in the partition, and a motor-blower unit mounted in the housing adjacent the said opening for drawing air therethrough into the second chamber, and a diffuser associated with the discharge end of the blower for confining the discharge air to expand gradually so as to be effective in converting some of the velocity air pressure to static air pressure, and a main air exhaust port in the top wall of the housing adjacent the front portion and for nearly the complete width thereof for discharging the air in an upward direction, a charcoal filter medium interposed over the exhaust port, and a secondary air exhaust port adjacent the lower front edge of the housing and being formed by a thin elongated gap, duct work adjacent the main air exhaust port for drawing off some of the air to the secondary air exhaust port so as to bypass the charcoal filter and discharge in a downward direction toward the cooktop thereby tending to break-up an upward air stream that would normally be induced across the front of the housing by the main exhaust stream.

5. A recireulating air cleaner such as is recited in claim 4 where at least a portion of the bottom wall of the housing is formed by a pivoted cover member, and fastening means for holding the cover in place, a source of illumination positioned behind the cover and a translucent w-indow assembled in the cover for directing light beneath the housing, said cover serving as access means to both the grease filter medium and the particulate filter medium as well as to the source of illumination.

6. A recirculating air cleaner that is adapted to be located above -a Cooktop -of a domestic range, said air cleaner comprising walls forming a hollow housing, a `botto-m wall of the housing having an air inlet port adjacent the front edge thereof, a first plenum chamber downstream of the air inlet port, a second plenum chamber, and a partition separating the first plenum chamber from a second plenum chamber, said partition including a small opening, a motor-blower unit mounted in said opening for drawing air from the first to the second plenum, at least one air filtering mediu-rn interposed upstream of the motor-'blower unit, the housing having a top wall with a main exhaust port adjacent the front edge thereof and communicating with the blower for directing the exhaust in an upward direction, a second air filtering medium associated with the main exhaust port, and a secondary exhaust port connected with the blower and being of thin elongated configuration, Iand duct work for drawing off some of the air from the main exhaust port so as to discharge air in a downward direction to attenuate the upward air stream that would normally be induced by the main exhaust stream.

References Cited by the Examiner UNITED STATES PATENTS 2,016,033 10/ 1935 Christofferson. 2,392,038 1/ 1946 Gaylord. 2,886,124 5/ 1959 Scharmer. 3,034,772 5/1962 Schultz 55-387 3,075,335 1/1963 Bandlow. 3,131,687 5/1964 Kalla. 3,176,447 4/1965 Omohundro et al. 55-472 X FOREIGN PATENTS 206,258 10/ 1939 Switzerland.

HARRY B. THORNTON, Primary Examiner.

B. NOZICK, Assistant Examiner. 

3. A RECIRCULATING AIR CLEANER THAT IS ADAPTED TO BE LOCATED ABOVE A COOKTOP OF A DOMESTIC RANGE, SAID AIR CLEANER COMPRISING WALLS FORMING A HOLLOW HOUSING HAVING AN AIR INLET PORT, A FIRST FILTER MEDIUM INTERPOSED IN THE INLET PORT, A PLENUM CHAMBER POSITIONED DOWNSTREAN OF THE FIRST FILTER MEDIUM, A SECOND FILTER MEDIUM POSITIONED IN THE PLENUM CHAMBER, A MOTOR-BLOWER UNIT MOUNTED IN THE HOUSING FOR DRAWING AIR FROM THE SAID PLENUM CHAMBER, AND A MAIN AIR EXHAUST PORT CONNECTED WITH THE BLOWER, THERE BEING A THIRD FILTER MEDIUM LOCATED WITHIN SAID MAIN EXHAUST PORT, AND A SECONDARY EXHAUST PORT CONNECTED WITH THE BLOWER AND BEING OF THIN ELONGATED SHAPE, AND DUCT WORK ADJACENT THE MAIN EXHAUST PORT FOR DRAWING OFF SOME OF THE AIR TO THE SECONDARY AIR EXHAUST PORT SO AS TO DISCHARGE AIR IN A DOWNWARD DIRECTION TOWARD THE COOKTOP IN THE MANNER OF AN AIR CURTAIN SO AS TO DIRECT THE AIR BENEATH THE HOUSING TOWARD THE INTAKE PORT. 